Fresnel volumes corresponding to PKP waves in the IASP91 model

Fresnel volumes provide a suitable tool for estimating the resolution limit s or accuracy of tomographic methods based only on the arrival times of the se seismic waves, which penetrate the deep interior of the Earth. The stand ard definition of the Fresnel volume was modified to include effects of mul tipathing, i.e., multivalued travel times. Computations were performed in t he IASP91 model for three representative epicentral distances and two preva iling signal periods. Preliminary results have been obtained. They place a rather strong restriction on the resolution limits of tomographic methods, depending on the prevailing period, due to the relatively large fatness of PKP Fresnel volumes.